| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply device that can properly cope with an overcurrent in accordance with its cause in a range not to be excessive. SOLUTION: In the switching power supply device that feeds current supply from a master power supply 1 to load 5, 6 by switching it by an output transistor 2 and smoothing it by a coil 3 and a capacitor 4, a voltage detected by an output current of the output transistor 2 is compared with reference values of two levels by comparators 11, 12, and counted by a counter 22 only in a period that the detected voltage reaches the second reference value after reaching the first reference value. When the detected voltage reaches the second reference value before the counter 22 reaches a first reference time, the current supply is stopped. When the counter 22 reaches a second reference time before the detected voltage reaches the second reference value, a duty ratio is lowered and the load 6 is disconnected. COPYRIGHT: (C)2006,JPO&NCIPI
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